Monday, towards the end of my brick training, I was moving at a swift clip, pumping my legs with purpose, and I ran strong through a right turn, leaning into it. Yeouch! A very brief, but very sharp pain in the middle of the arch of my left foot (essentially the softest spot of your feet). Not so good. I was less than a mile from home. I changed my gait slightly and just finished the run. No problem.
The following day, it didn't happen again, but my left arch just started to feel weak. I noticed myself slowly changing my gait throughout the run, trying to put less weight on my left foot and stay more on the outsides of my feet. Even if you're doing that kind of thing to try and avoid injury, it's never good when you're running improperly. My arch continued to feel weak for the rest of the day, and even still felt just a little strange the following morning. Knowing what plantar fasciitis is, and having watched it keep one of my co-workers from running for months at a time, I erred on the side of caution and took a day off on Wednesday.
I'm guessing that I just over-stressed my feet a little on my backpacking trip last weekend. 20 miles/day, rough terrain, and an extra 25 pounds on your back can probably take a slow toll on your body. I figured it would be my knees or ankles, but apparently it was the arch of one of my feet.
Thursday I got back in business and took off for an all-paved 12-mile run. I almost never run on pavement these days, but with the San Francisco Marathon coming up in a few weeks, I want to get used to the surface, and also get used to my road shoes. I was hoping to stay under a 6:20/mile pace, but I guess I forgot what a difference light shoes, flat topography, and a firm surface can do for you. When the 12 miles were up, I had averaged a 6:01/mile pace, skewed upwards by a slow start (6:41 in the first mile). I guess my feet are strong enough again.